conf: reduce readiness file stat() initial interval

Sometimes even if the readiness file exists the os.Stat() call will
return "file not found". This causes GetReadinessIndicatorFile() to
wait 1 second during performance critical operations, even if the
os.Stat() would have returned success quickly after the first
failure.

Add a short backoff up to 1.2s before falling back to the longer
intervals. The exponential backoff shouldn't add too much stress
to the filesystem, but should allow quicker detection of the
readiness file on each container operation.

Signed-off-by: Dan Williams <[email protected]>

pkg/types/conf.go

@@ -615,6 +615,21 @@ func CheckSystemNamespaces(namespace string, systemNamespaces []string) bool {
 
 // GetReadinessIndicatorFile waits for readinessIndicatorFile
 func GetReadinessIndicatorFile(readinessIndicatorFile string) error {
+	// Quick first backoff up to ~1 second
+	backoff := utilwait.Backoff{
+		Steps:    5,
+		Duration: 75 * time.Millisecond,
+		Factor:   2.0,
+		Jitter:   0.1,
+	}
+	if utilwait.ExponentialBackoff(backoff, func() (bool, error) {
+		_, err := os.Stat(readinessIndicatorFile)
+		return err == nil, nil
+	}) == nil {
+		return nil
+	}
+
+	// Otherwise wait a longer time until the file exists
 	pollDuration := 1000 * time.Millisecond
 	pollTimeout := 45 * time.Second
 	return utilwait.PollImmediate(pollDuration, pollTimeout, func() (bool, error) {